Influence of carotid endarterectomy on choroidal perfusion (INFLATE Study)

Abstract

Purpose : To determine if carotid artery endarterectomy (CEA) caused a change in choroidal perfusion, patients with significant internal carotid artery stenosis (CAS) underwent swept-source tomography angiography (SS-OCTA) and choroidal vascular parameters were measured before and after their surgery.

Methods : Patients were diagnosed with clinically significant unilateral CAS and enrolled in this prospective observational study (INFLATE Study). SS-OCTA (PLEX Elite 9000, Carl Zeiss Meditec) imaging using the 6x6mm scan protocol centered on the fovea was performed on all subjects before and within 2 weeks after CEA. Previously validated algorithms were used to measure the mean choroidal thickness (MCT), choroidal vascular index (CVI) within 2.5mm and 5mm circles centered on fovea, and choriocapillaris flow deficits (CCFDs) within 3mm and 5mm circle centered on fovea.

Results : 112 eyes from 56 patients with a mean age of 72.80 ± 7.62 years were included in the study. A statistically significant negative correlation was found between age and preoperative MCT in both the 2.5mm (stenotic: R=-0.31, p=0.018; non-stenotic: R=-0.30, p=0.027) and 5mm circles (stenotic: R=-0.34, p=0.011; non-stenotic: R=-0.34, p=0.011). There were significant increases (10±14 % increase in 2.5mm; 9±12% increase in 5mm) in the MCT following CEA on the stenotic side after surgery in both the 2.5mm (229.62±77.23 versus 253.57±91.11, p<0.0001) and the 5mm (222.67±71.18 versus 241.93 ±78.87, p<0.0001) circles. In contrast, MCT did not change significantly on the non-stenotic side in either the 2.5mm (p=0.337) or the 5.0mm (p=0.303) circles. Furthermore, CVI and CCFDs remained unchanged before and after CEA on either stenotic (CVI:2.5mm p=0.844, 5mm p=0.577; CCFDs:3mm p=0.71, 5mm p=0.62) or non-stenotic sides (CVI: 2.5mm p=0.225, 5mm p=0.298; CCFDs:3mm p=0.98, 5mm p=0.9).

Conclusions : A significant increase in MCT following CEA in eyes on the ipsilateral side of significant carotid stenoses suggests that this change was a direct effect of improved choroidal perfusion after surgery. However, no corresponding changes were noted in CVI, consistent with previous findings that CVI is independent of choroidal thickness. No changes were found in CCFDs, suggesting that measurements of CCFDs may not correspond to increased CC blood volume, and the measurement of CC thickness and blood flow velocity are needed.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.